Post-operative central hypersensitivity and pain: the pre-emptive value of pethidine for ovariohysterectomy.
The effect of timing of analgesic drug administration on the severity of post-operative pain was investigated in dogs undergoing ovariohysterectomy using both subjective visual assessment scoring systems (VAS) and objective mechanical nociceptive threshold measurements using a novel handheld anti-nociceptiometric device. Forty dogs undergoing routine elective ovariohysterectomy were included in a randomised and double-blind study and assigned to one of three groups: (i) pre-operative analgesics; (ii) post-operative analgesics; (iii) no analgesics (saline injections). The analgesic used was pethidine (a short acting predominantly mu-opioid agonist), at a dose of 5.0 mg/kg (intramuscular). The post-operative administration of pethidine resulted in significantly higher sedation scores and significantly lower pain scores in the early post-operative period, but the dogs given pethidine pre-operatively had significantly lower pain scores than both the other groups at 8, 12 and 20 h post-extubation (P < 0.01, ANOVA). Mechanical thresholds measured at the distal tibia demonstrated the development of allodynia at 12 and 20 h post-extubation, and this was significantly prevented by the pre- (P < 0.01 at 12 h, P < 0.05 at 20 h, Kruskal-Wallis and post hoc Dunn's), but not by the post-operative administration of pethidine. Mechanical nociceptive thresholds measured at the ventral midline (site of surgery) demonstrated post-operative hyperalgesia in all groups; this hyperalgesia was least in the pre-operative pethidine group. In summary, this study clearly shows pethidine to be an effective analgesic in dogs, albeit of short duration of action, when administered post-operatively, and, importantly, that it has a positive benefit in terms of post-operative outcome measures, when administered pre-operatively, possibly as a result of blocking or preventing the development of central sensitisation following surgical stimulation.
Lascelles
X B D
XBD
Department of Clinical Veterinary Science, Division of Companion Animal Studies, Langford House, Langford, Bristol, BS18 7DU, UK Department of Clinical Veterinary Science, University of Cambridge, Queen's Veterinary School Hospital, Madingley Road, Cambridge, CB3 OES, UK.
Cripps
J P
JP
Jones
A
A
Waterman
E A
EA
D000005:Abdomen; D000701:Analgesics, Opioid / Q000627:therapeutic use*; D000704:Analysis of Variance; D000818:Animals; D004285:Dogs; D004311:Double-Blind Method; D005260:Female; D006967:Hypersensitivity / Q000209:etiology*; D007044:Hysterectomy / Q000009:adverse effects / Q000662:veterinary*; D008614:Meperidine / Q000627:therapeutic use*; D010052:Ovariectomy / Q000009:adverse effects / Q000662:veterinary*; D017288:Pain Threshold; D010149:Postoperative Pain / Q000517:prevention & control / Q000662:veterinary*; D011884:Radius; D013314:Stress, Mechanical; D013977:Tibia
D000701:Analgesics, Opioid; D008614:Meperidine